Method of rendering fabrics waterrepellent and product resulting therefrom



Patented Mar. 11, 1952 METHOD OF RENDERING FABRICS WATER-e REPELLENT AND PRODUCT RESULTING THEREFROM 'Firth L. Bennett, Midland, Mich., assignor to Dow Corning Corporation, Midland, Mich.,. a

corporation of Michigan No Drawing. Application November 10, 1949, Serial No. 126,690

3 Claims.

This invention relates to a method of rendering fabrics water-repellent.

Siloxanes for treating fabrics to renderthem water-repellent have heretofore been known. Mark-off is a serious problem in connection with the heretofore known compositions. Marl:- off is the appearance of lines when the treated fabric is folded or otherwise wrinkled. Mark-01f appears especially in such fabrics as nylon, orlon and rayon of either viscose or acetate type. Heretofore, when the treated fabric was laundered or dry cleaned, a considerable amount of the objectional mark-off was noted.

It is an object of the present invention to provide a method whereby fabrics are rendered substantially water-repellent even after laundering and dry cleaning.

It is another oject of the present invention to eliminate or materially reduce mark-oil in fabrics rendered water-repellent, such as nylon, orlon and rayon of either viscose or acetate type.

It is a further object of the present invention to render fabrics water-repellent whereby the fabrics after treatment possess good hand and drape, and are of better crease resistance.

In accord with the present invention, fabrics are rendered water-repellent by wetting the fabrics with a mixture of two organosiloxane polymers. The fabrics so wetted are then heated at a temperature ranging from 100 to 475 F. for a period of from seconds to 1 hour.

The fabrics which may be treated in accord with the method of the present invention include fabrics of natural materials such as cotton, linen, silk or wool and fabrics. of artificial material such as nylon, orlon and rayon of either viscose or acetate type.

One of the siloxane polymers used in the above stated mixture is a methylhydrogenpolysiloxane fluid which contains between 1.0 and 1.5 methyl radicals and between 0.75 and 1.25 hydrogen atomsbonded to silicon per silicon atom, there being a total of 2 to 2.25 methyl radicals and hydrogen atoms per silicon atom. Fluids of this type may be produced by the hydrolysis and con densation of CH3HS1C12 alone or by cohydrolyzing and condensing it with a chlorosilane, such as (CH3)3SiCl; (Cl-mzl-lsiCl; and (CH3)2SiC1z.

The other siloxane polymer used in the above stated mixture is a methylpolysiloxane fluid which contains between 2 and 2.1 methyl radicals per silicon atom and which has a viscosity of at least 1,000 centistokes and preferably less than 100,000 centistokes. Such fluids and their preparation have been described in the art and are now well-known commercially. They may be produced by cohydrolyzing and condensing a mixture of methyl chlorosilanes of the general average formula (CHs)nSiCl4 n where n has a value of from 2 to 2.1.

From 20 to '70 per cent by weight of the total mixture consists of the methylpolysiloxane and the remaining to 30 per cent consists of the methylhydrogenpolysiloxane.

Catalysts may be added to the mixture of organosiloxanes, and the mixturethen used to wet the fabric. Alternatively the fabric may be wetted with the organosiloxane mixture and the fabric dippedin a solution of the catalyst. Such catalysts include metallic salts such as sodium bicarbonate, sodium aluminate and iron, cobalt, manganese, lead and zinc salts of carboxylic acids such as acetates, octoates and naphthenates.

This organosiloxane mixture may be applied directly to the fabric.- However, it is preferred to extend the organosiloxane mixture by diluting with a liquid hydrocarbon, chlorohydrocarbon, ether or alcohol, such as benzene, dioxane, ethanol or the like inorder to minimize the amount employed.

The organosiloxane mixture may likewise be extended by the preparation of an aqueous emulsion, which emulsion preferably contains an emulsifying agent decomposible by heating. The quaternary ammonium halides are examples of such emulsifying agents. They are decomposed on heating for a brief period before the fabric is damaged by the heating. Examples of such halides are the alkylarylammonium chlorides, such as trimethylbenzylammonium chloride and hexadecyldimethylbenzylanimonium chloride. If desired, the siloxane mixture may be thinned with any of the above indicated solvents in order to facilitate emulsification. After emulsification, the solvent may be removed under vacuum, if desired.

Emulsions of methylhydrogenpolysiloxanes frequently liberate hydrogen upon standing. In order to avoid this effect, it is accordingly desirable to add an organic acid such as acetic acid to the emulsion in order to inhibit the evolution of hydrogen. The quaternary ammonium salts function well as emulsifying agents in such acid syfiilfims.

The siloxane mixture either straight or as a solution or emulsion may be applied to the fabric in any appropriate manner. Thus, the fabric may be dipped in the mixture. The mixture may be applied to the fabric by the use of conven tional equipment such as a padder or ql etch.

The fabric may then be dried to remove water or solvent.

The material should be applied to the fabric in such amount that there is between 1 and 5 per cent of the organosiloxane mixture based upon the weight of the fabric.

The fabric is then heated to between 100 and 475 F. for from 5 seconds to 1 hour. This heating efifects liberation of a major portion of the hydrogen which is bonded to the silicon in the methylhydrogenpolysiloxane. The decomposition product is polymerized to an insoluble polymer in the fabric, whereby the fabric is rendered permanently hydrophobic. When a heat decomposable emulsifying agent is employed, it is also decomposed during thisheating.

The present invention is of particular importance in the hydrophobing of nylon and acetate rayon. In manufacturing filaments of these materials, the filaments are extruded in a molten state and the extrusion stretched while soft.

This results in a strain in the filaments. Frequently the fabrics are woven without the strain in the filaments being relaxed. Such a fabric may be wetted with a siloxane in accord with this invention. After wetting, the fabric is contacted with a hot surface at a temperature of 400 to 475 F. for from 5 to 80 seconds. This heat treatment serves a dual purpose, first, to set the siloxane polymer and second, to effect relaxation of the filament. The use of the siloxane improves the ironability of the fabric, since the coated fabric does not adhere to the iron nor do the fibers cohere even when slightly softened.

Fabrics treated in accord herewith are substantially water-repellent both after laundering and after dry cleaning. The contact angle between a drop of water and the surface of a fabric so treated is about 110. Treated fabrics of cotton, linen, wool, nylon, orlon and rayon are soft to the touch and have a good hand. Nylon, orlon and rayon fabrics so treated have a reduced tendency to show mark-off.

The following polysiloxanes were prepared:

A mixture of, 9.3 parts by weight of decamethyltetrasiloxane and 735 parts of octamethylcyclotetrasiloxane was prepared. To this mixture there were added .56 part of KOH. This mixtures was then heated at 160 C. for 8 hours. The mixture was then cooled to about 100 C. and CO2 in the form of Dry Ice was added over a period of 30 minutes. This mixture was then filtered and flash distilled to 250 C. at 1 mm. pressure. There were obtained 625 parts of a trimethylsiloxy end-blocked dimethylpolysiloxane fluid having a viscosity of 1,000 centistokes, which is referred to as product I in the examples.

A mixture was prepared of 1.5 parts by weight of decamethyltetrasiloxane and 735 parts of octamethylcyclotetrasiloxane. To this mixture there were then added .56 part of KOH. This mixture was'then agitated and heated at 160 C. for 8 hours. The mixture was then cooled to about 100 C. and CO2 in the form of Dry Ice added over a period of 30 minutes. The mixture was then filtered and flash distilled to 250 C. at 1 mm. pressure. There were obtained 630 parts of a trimethylsiloxy end-blocked dimethylpolysiloxane fluid having a viscosity of 12,500 centistokes, which is referred to as product II in the examples.

A mixture was prepared of 1.2 parts by weight of decamethyltetrasiloxane and 735 parts of octamethylcyclotetrasiloxane. To this mixture there was then added .56 part of KOH. The mixture was then agitated-and heated at 160 C. for

8 hours. The mixture was then cooled to C.

To this mixture 675 parts of isopropyl alcohol were added over a period of 10 minutes and then 783 parts of water were added over a period of 1 hour, whereby to effect hydrolysis. An additional 750 parts of benzene were then added to the reaction mixture. The product was washed six times with water and strip distilled at 3 mm. pressure to C. to remove the benzene and the lower boiling products. There were obtained 475 parts of a trimethylsiloxy end-blocked methylhydrogenpolysiloxane, which is referred to as product IV in the examples.

In the following examples, which are illustrative only, the spray rating was determined by standard test method 22-41 of the American Association of Textile Chemists and Colorists.

Example 1 A mixture was prepared of 24 parts by weight of product IV and 6 parts of product I. To this siloxane mixture there were added 3 parts of hexadecyldimethylbenzylammonium chloride and Example 2 A mixture was prepared of 24 parts by weight of product IV and 6 parts of product II. To this siloxane mixture there were then added 3 parts of hexadecyldimethyl-benzylammonium chloride and 0.1049 of acetic acid. The resulting mixture was then emulsified with 967 parts of water using a colloid mill. This produced an emulsion containing 3 per cent siloxane. The emulsion was employed for treating acetate rayon. One sample of the fabric was heated aftertreating at a temperature of C. for 5 minutes. Following this the fabric had a spray rating of 90. The fabric was next Washed with soap, following which it had a spray ratin of 80 to 90. It was noted that the fabric was free of objectionable mark-off.

Example 3 A mixture was prepared of 18 parts by weight of product IV, 15 parts of water, 19 parts of toluene and 12 parts of product II. To this siloxane mixture there were then added 3 parts of hexadecyldimethylbenzylammonium chloride. The resulting mixture was then emulsified with 942 parts of water using a colloid mill. The emulsion produced contained 3 per cent of siloxane. This emulsion was employed for treating the following fabrics for and minutes at 150 C. giving the spray rating indicated.

5 min./ 10 min./ 150 C. 150 C ('1?) Muslin 90 90 (2) Plaid Twill 90 100 (3) Acetate Sharkskin 90 100 The rayon fabric was free of objectionable marl;- off.

Example 4 ing in the indicated spray ratings:

(1) Muslin 100 (2) Olive elkskin (cotton and viscose rayon) 100 (3) W001 twill 90 (4) Acetate sharkskin 100 (5) Acetate French crepe 70 (6) Acetate satin 70 (7) Acetate and rayon faille 90-100 (8) Viscose rayon suiting 100 The treated fabrics had a good hand, and the rayon fabrics were free of objectionable markoff.

Example 5 A mixture was prepared of 354 parts by weight of methylene chloride, 248.5 parts of water and 177 parts of product III. To this mixture there were then added 17 parts of hexadecyldimethylbenzylammonium chloride, and the mixture emulsified using a colloid mill. This emulsion was added to 154 parts of product IV. 10,000 parts of water were then added to the emulsion. The mixture was then emulsified using a colloid mill. The following fabrics Were treated for 5 minutes at 150 C. after which time the fabrics had the spray ratings indicated:

(1) Muslin 80 (2) Cotton twill 80 (3) Acetate rayon 90 (4) Nylon tenting M 100 The fabrics all had a good hand and the rayon and nylon fabrics were free of objectionable mark-off.

Example 6 A solution was prepared of 194 parts by weight of toluene, 3.6 parts of product IV and 2.4 parts of product II. Acetate rayon twill fabric was coated with this solution and the fabric cured for 10 minutes at 450 F. Following this, the fabric had a spray rating of 80. The fabric had a good hand and was free of objectionable markoff.

Example 7 A solution was prepared of 194 parts by weight of toluene, 2.4 parts of product IV and 3.6 parts of product II. An acetate rayon twill was coated with this solution and cured for 10 minutes at 150 0. Following this, the spray rating was 80.

The fabric was soft and was free of objectionable mark-off.

Example 8 A solution was prepared of 194 parts by weight of toluene, .78 part of product IV and 5.22 parts of product II. Acetate rayon twill was coated with this solution and cured for 10 minutes at 150 C. Following this, the spray rating of the fabric was 90. The fabric had a good hand. The fabric was" free of objectionable mark-off. Following dry cleaning the fabric had a spray rating of 70.

Example 9 A mixture was prepared of 1405 parts by weight of product IV, 935 parts of product II and 1260 parts of methylene chloride. To this siloxane mixture there were then added 234 parts of hexadecyldimethylbenzylammonium chloride. The resulting mixture was then emulsified with 2016 parts of water using a colloid mill. The emulsion produced was diluted with 52,650 parts of Water. This gave an emulsion containing 4 per cent of siloxane. This emulsion was employed for treating the following fabrics for 5 minutes at 150 C. giving the spray rating indicated:

(1) Muslin 100 (2) Cotton twill 100 (3) Orlon 100 (4) Nylon 100 (5) Nylontenting 100 (6) W001 100 (7) Acetate twill 100 (8) Acetate sharkskin 100 All of the above fabrics had a soft hand, and the rayon, nylon and orlon fabrics were free of objectionable mark-off.

That which is claimed is:

1. The method of rendering organic fabrics l. water-repellent, which comprises wetting the fabrics with a mixture of from 20 to '70 per cent by Weight of a methylpolysiloxane containing between 2 and 2.1 methyl radicals per silicon atom and having a viscosity of at least 1,000 centistokes v and less than 100,000 centistokes, and from 80 to 30 per cent of a methylhydrogenpolysiloxane containing between 1.0 and 1.5 methyl radicals and between 0.75 and 1.25 hydrogen atoms bonded to silicon per silicon atom, there being a total of 2 to 2.25 methyl radicals and hydrogen atoms per silicon atom, and heating the wetted fabrics at a temperature of from to 475 F. for a period of from 5 seconds to 1 hour, whereby the fabrics are rendered water-repellent.

2. The method of rendering organic fabrics water-repellent, which comprises wetting the fabrics with an aqueous emulsion of a mixture of from 20 to 70 per cent by weight of a methylpolysiloxane containing between 2 and 2.1 methyl radicals per silicon atom and having a viscosity of at least 1,000 centistokes and less than 100,000 centistokes, and from 80 to 30 per cent of a methylhydrogenpolysiloxane containing between 1.0 and 1.5 methyl radi als and between 0.75 and 1.25 hydrogen atoms bonded to silicon per silicon atom, there being a total of 2 to 2.25 total methyl radicals and hydrogen atoms bonded to silicon per silicon atom, which emulsion contains a trialkylbenzylammonium chloride as an emulsifying agent, and heating the wetted fabric at a temperature of from 100 to 475 F. for a period of from 5 seconds to 1 hour, whereby the fabrics are rendered water-repellent and the emulsifying agent is decomposed.

3. An organic textile fabric coated with between 1 and 5 per cent based upon the weight of the fabric of a polymerized mixture of from 20 to 70 per cent by weight of a methylpolysiloxane containing between 2 and 2.1 methyl radicals per silicon atom and having a viscosity of at least 1,000 centistokes and less than 100,000 centistokes, and from 80 to 30 per cent of a methylhydrogenpolysiloxane containing between 1.0 and 1.5 methyl radicals and between 0.75 and 1.25 hydrogen atoms bonded to silicon per silicon atom, there being a total of 2 to 2.25 methyl radicals and hydrogen atoms per silicon atom.

FIRTH L. DENNETT.

REFERENCES CITED The following references are of record in the file of this patent:

Number 8 UNITED STATES PATENTS Name Date Rochow Oct. '7, 1941 Britton June 9, 1942 Patnode Dec. 22, 1942 Tucker Mar, 16, 1943 McGregor Sept. 4, 1945 Morton Oct. 9, 1945 Hyde Dec. 4, 1945 Biefeld Jan. 15, 1946 Sarbach Feb.- 19, 1946 West Mar. 26, 1946 Tanis, Jr. Oct. 8, 1946 Hyde Apr. 13, 1948 Welsh Sept. 21, 1948 Wilcox Dec. 20, 1949 Warrick Jan. 17, 1950 MacKenzie Mar. 14, 1950 Rust Nov. 7, 1950 

1. THE METHOD OF RENDERING ORGANIC FABRIC WATER-REPELLENT, WHICH COMPRISES WETTING THE FABRICS WITH A MIXTURE OF FROM 20 TO 70 PER CENT BY WEIGHT OF A METHYLPOLYSILOXANE CONTAINING BETWEEN 2 TO 2.1 METHYL RADICALS PER SILICON ATOM AND HAVING A VISCOSITY OF AT LEAST 1,000 CENTISTOKES AND LESS THAN 100,000 CENTISTOKES, AND FROM 80 TO 30 PER CENT OF A METHYLHYDROGENPOLYSILOXANE CONTAINING BETWEEN 1.0 AND 1.5 METHYL RADICALS AND BETWEEN 0.75 AND 1.25 HYDROGEN ATOMS BONDED TO SILICON PER SILICON ATOM, THERE BEING A TOTAL OF 2 TO 2.25 METHYL RADICALS AND HYDROGEN ATOMS PER SILICON ATOM, AND HEATING THE WETTED FABRICS AT A TEMPERATURE OF FROM 100* TO 475* F. FOR A PERIOD OF FROM 5 SECONDS TO 1 HOUR, WHEREBY THE FABRICS ARE RENDERED WATER-REPELLENT. 